What's Actually Happening Here
The NS_E_DRM_MUST_REVALIDATE error (0XC00D28A7) means Windows Media Player or a UWP app that uses PlayReady DRM can't reach the license server to check if your device is still trusted. This happens after you haven't renewed your DRM credentials for a while — usually 90 days by default. It's not a broken file or a bad install. It's a stale security handshake.
You'll see this in Windows Media Player when trying to play a purchased or rented file, or in apps like Netflix, Hulu, or Amazon Prime Video that rely on PlayReady. The trigger is often a long gap between uses, a system date change, or a Windows update that reset the DRM components.
Fix 1: Re-Login or Reboot (30 seconds)
Start here. The simplest revalidation is forcing the DRM client to re-authenticate. Log out of the app that's throwing the error, then log back in. If that doesn't work, reboot the machine — a cold restart clears the DRM memory cache and forces a fresh handshake on next launch.
Wait — if you're using Windows Media Player, there's no login. In that case, just close the player completely and reopen it. The DRM manager runs as a background service, and a restart of the service often nudges it to revalidate.
Why this works: The DRM client caches your license state in memory. A reboot clears that cache, so the client has no choice but to contact the license server again. If your network is fine and the server is reachable, that's all you need.
Fix 2: Clear the DRM Cache (5 minutes)
If the quick fix didn't take, the DRM cache on disk is probably corrupted or holding an expired license. Windows stores DRM data in a hidden folder under your user profile. You can delete it safely — Windows rebuilds it on next use.
- Press Win + R, type
%USERPROFILE%\AppData\Local\Microsoftand hit Enter. - Look for a folder called
PlayReady. If it's not there, look forDRM(in older Windows versions). - Right-click it and delete it. You might get a UAC prompt — accept it.
- Now go to
%USERPROFILE%\AppData\Local\Packagesand find the folder for your app. For Netflix, it'sNetflix.Nflix_...; for Windows Media Player, there's no per-app folder — the DRM cache is the one you just deleted. - If you found the app's folder, open it and delete the
LocalCachesubfolder. Don't delete the whole package folder—that breaks the app.
After that, restart the app. It'll rebuild the DRM cache and do a fresh revalidation.
Why this works: The DRM cache stores your license tokens and device certificates. If that file is corrupt — often from a sudden power loss or a poorly timed update — the client fails to validate and throws this exact error. Deleting it forces a clean slate.
Fix 3: Reset PlayReady (15+ minutes)
This is the nuclear option, but it's the one that actually fixes persistent revalidation loops. You're going to reset the entire PlayReady DRM system on your machine. This requires admin rights and a reboot.
Step 1: Check the date and time
Before you nuke everything, make sure your clock is right. A wrong system time breaks DRM immediately — the license server sees your request as expired or future-dated. Go to Settings > Time & Language > Date & Time and toggle on "Set time automatically." If that's already on, turn it off, then on again, and sync manually.
Step 2: Uninstall the app (for UWP apps)
For Netflix, Amazon, etc., right-click the app in Start menu and choose Uninstall. Then reinstall from Microsoft Store. This resets the app's DRM state because the app package holds a copy of the PlayReady data.
For Windows Media Player, it's a Windows feature, so you can't uninstall it that way. Instead you'll do the PlayReady reset below.
Step 3: PlayReady reset
Open an elevated Command Prompt (right-click CMD, run as administrator) and run:
reg delete "HKLM\SOFTWARE\Microsoft\PlayReady" /f
reg delete "HKCU\SOFTWARE\Microsoft\PlayReady" /f
Then delete the PlayReady folder from Fix 2 again, just to be thorough.
Step 4: Restart and reinstall
Reboot. Then reinstall any UWP app you uninstalled. For Windows Media Player, just open it — Windows will recreate the registry keys and rebuild the DRM cache automatically.
Why this works: The registry keys hold the device's DRM ID and the revalidation counter. Deleting them makes the DRM client think it's a brand new device, so it does a full revalidation from scratch. The catch: you might need to re-authenticate to your streaming services, and any licenses tied to your old device ID are gone. That's fine for rentals that are still within the playback window — they'll re-download.
When None of This Works
If you've done all three and still get the error, check for a firewall or VPN blocking the license server. PlayReady calls out to playready.microsoft.com — if your VPN routes through a country where the service is blocked, the handshake fails silently. Temporarily disable the VPN, or exclude that domain in your firewall.
Also check if your Windows build is ancient — DRM gets updated with OS patches. Run Windows Update and install everything. I've seen this error on Windows 10 1809 that wouldn't go away until after a feature update.
The Real Takeaway
This error is rarely a sign of something broken. It's your DRM doing its job a little too well. The 30-second fix handles most cases. The cache clear handles the next chunk. The registry reset is the last resort, and it's worked for me every time I've needed it. Don't skip the date check — I've wasted twenty minutes trying to clear a cache that was fine, only to realize my BIOS battery was dead.